Electrical instrument.



O.A.KNOPB ELECTRICAL INSTRUMENT.

APPLICATION FILED JULY 2. I9I4.

1 1 '7 1 ,2 1 3 Patented Feb. 8, 1916.

2 SHEETS-SHEET I.

0. A. KNOPP.

ELECTRICAL INSTRUMENT.

APPLICATION FILED JULY 2. I914.

Patented Feb. 8, 1916.

2 SHEETS-SHEET 2.

'C v u u WG W ' UNITED STATES PATENT ()FFICE.

OTTO A. KNOPP, OF OAKLAND, CALIFORNIA.

ELECTRICAL INSTRUMENT.

To all whom it may concern: Be it known that I, Orro A. K 1\ or1 a citizen of the United States, residing in Oakland, Alameda county, State of California,

ment of the above noted class which will automatically operate to give indications or records and which, in one form at least, shall be applicable either to alternating or to direct current circuits.

A further object of the invention is to provide an electrical instrument of the above noted type in which the .current in the secondary coil or circuit is automatically varied when the primary winding or circuit is energized until the magnetic fields set up by said two windings neutralize each other and in which the amount of current necessary to cause such neutralization is indicated or recorded bv a suitable instrument, which may be calibrated in any desired manner.

These objects and other advantageous ends I secure as hereinafter set forth, reference being had to the accompanying drawings, in

. which,

Figure 1 isa diagrammatic representation of one arrangement of apparatus for carrying out my invention; Fig. 2 is an elevation, partly in section, illustrating certainv detail features of the invention; Fig. 3 is a diagrammatic representation of a slightly modified form of my invention; and, Fig. 4 is a diagrammatic view of a special form of apparatus particularly designed for use in measuring direct currents of high potential.

In Figs. 1 and 2 of the above drawings, 1 represents a conductor forming part of a circuit in which the current flow is to be measured, and for the purpose of accomplishing this end, I provide an annular core 2, preferably of laminated iron, having a segmental piece cut out of it so that its two ends are spaced apart a sufficient distance to permit of the introduction of the conductor. Upon the core I mount a winding 3, of suitable length and cross section, and bring its ends out to a air of terminals 4 and 5. A segmental casing 6 is designed to Specification of Letters latent.

fit in and practically fill the space between the spaced ends of the core'2, and in this is mounted a magnetic needle 7 free to swing in the plane of the core 2, though it normally tends to return to or remain in a position radial of said core. On said casing I provide three terminals or binding posts 8*,

8, and 9, and the first is connected to a contact 1O placed to be engaged by the needle 7 or by a structure movable therewith, whenever it swings in one direction through a predetermined angle from its neutral or normal position. A second contact 11 is placed on the opposite side of the needle 7 in position to be engaged when it swings in the opposite direction, and is connected to the terminal 9. The intermediate contact 8 is electrically connected to the needle 7 or to any contact structure which is movable therewith.

As shown in Fig. 2, the contact 10 is connected through its-terminal to one end of an electromagnetic winding 12, while the contact 11 is likewise connected to one end of a second electromagnetic winding 13. In the present instance, these electromagnets are shown as solenoids whose second ends are connected together and electrically connected thro 1gb a conductor 14 with one endof a body of resistance 15.

In order to normally retain the core 16 of the solenoids in its normal position midway between both of them or in any other predetermined definite position, as well as to return it to such position, I provide a cylinder 19 in which is operative a plunger 20 carried by or connected to the rod 17. This rod also carries between one end of the cylinder and the piston or plunger 20 a spring .21. In this case the magnetic needle 7 is permanently connected through a conductor Patented Fr b. 8,1916.

Application filed July 2, 1914. Serial No. 8&8,636.

signed to electrically engage any of a number of contacts connected to different narts the middle of its scale and may deflect in either direction. The spring 21 is attached at one end to one end of the cylinder 19 and its opposite end is likewise attached to the piston 20, so that, as above noted, it tends to maintain the core 16 in a position partly within and midway between the solenoids 12 and 13. If, now, the current flows in the conductor 1, there is a magnetic flux set up in the core 2 and the magnetic needle 7 is deflected from its normal position shown in Fig. 1, into engagement with one or the other of the contacts 10 or 11. If it be the former of these contacts which is engaged, the solenoid 12 is energized by current from the source 23 and the core 16 is therefore drawn into this's'olenoid. As a consequence, the spring 21 is compressed and the resistance arm 18 is so moved that some of the resistance of the bank 15 is cut out of circuit. The current flowing in the circuit formed by the source 23, winding 3, instrument 24c and resistance 15 is, therefore, increasedand said winding is so designed that this increased current flow tends to magnetize the core 2 in opposition to the magnetizing effect of the current in the conductor 1, until finally the magnetic flux in said core is reduced to such a point that the magnetic needle disengages the contact 10 and returns to its neutral or mid position. Obviously, the amount of current flowing in the circuit 23, 15, 24, and 3, when this condition exists, is indicated on or recorded by the instrument 21 and bears a definite relation to the current flow in the conductor 1 when the magnetic needle 7 finally disengages the contact 10. The spring 21 will then tendto move the core 16 with its attached parts back to the normal position, but since such movement would at once place additional resistance in circuit with the winding 3, the needle 7 would again be brought into engagement with the contact 10, thus again energizing the solenoid 12. Consequently, the solenoid core and the movable element of the instrument 24 are maintained at points whose position varies with the current flow in the conductor 1 and a continuous record or indication is given of such flow if the instrument is properly calibrated.

In that form of my invention shown in the contacts 10 and 11 are respectively 0011- nected to the solenoids 12 and 13. In order that the apparatus may be used in direct current'circuits, the conductor 22 includes a switch .28 which may be opened to break the circuit, and the direct current source 23 includes in its circuit two other switches 29 and 30 for connecting it to the two ends of the conductor 22 when this is broken by the I he winding 3 opening of the switch 28. of the core 2, while having one end connected to the instrument 24 as before, has its'second end connected to one blade of a doublethrow, double-pole switch 31, whereby it may be connected through a conductor in circuit with the conductor 22 and at the 8C 32 to the conductor 27 and thence to the line same time the switch 28 is open while the switches 29 and 30 are closed, while obviously themovable contact member for adjusting the resistance 26 is placed ina position in which the connection with the line 1" is broken. apparatus operates as described in connection with Fig. 1. ()n the other hand, if it be employed to measure an alternating current flow in the circuit of which the lines- Under these conditions, the

1 and 1 form a part, the switch 31 is moved to the position shown in Fig. 3, in which] case the winding of the magnetic needle is energized from the lines 1 and 1*, while the winding 3 and the parts in connection therewith are likewise connected across said main lines through the resistance 26, conductor 32, switch 31, winding 3, instrument 24, re-

sistance '15, conductor 22 and switch 31 to,

the line 1". As before, the magnetic field set up by the current in the conductor 1 causes a flux in the core 2 and the current in the winding 3 required to neutralize said flux sufliciently to keep the magnetic needle 7" out of engagement with the contacts 10 and 11, bears a definite ratio to the flow in the line 1". The instrument .24 may be calibrated to give direct readings of such flow. When this form of my invention is employed for use on direct current circuits after being used to measure alternating currents, it will be understoodthat if necessary the needle 7" may be polarized in any suitable manner so that it will deflect in the proper direction when the core 2 is excited.

It is to be noted that in the form of the invention shown in, Fig. 3, the battery or direct current source 23 furnishes the exciting current for the winding of the needle 7 when the apparatus is modified for use 'in direct current circuits and also furnishes 'switch 31 substitutes alternating current from the line for the direct current in the winding 3, it being necessary that the current for excitation and compensating be in phase with the line current. Obviously, therefore, the line current can be used for the above noted purpose when the line circuit is not inductive and for inductive current circuits the secondary alternating cur rent source is to 'be'provided either from a shunt in series with the line or from the secondary of a current transformer whose primary is in series with the line.

In Fig. 4, I have shown the invention as designed for use in measuring direct currents of high potential, and in this case the core 2 has one winding 35 connected between the line conductors through a body of resistance26, with a second or compensating winding 3 connected as described in the ar rangement of Fig. 1. As in the instrument shown in Fig. 3, the magnetic flux produced in the core 2 by the winding 35 or by a conductor 1, is automatically neutralized by the operation of the solenoids 12 and 13, one or the other of which acts to vary the amount of the resistance in circuit until such neutralization is completed by reason of the current flowing in the secondary winding 3. Since the apparatus is so designed that the solenoid core 16 holds the resistance arm 18 in the proper position to cause the current flow through said winding to remain at or near its neutralizing strength, the instrument 24, being properly calibrated, gives the indication or record of the current flow in he line conductors.

It is to be understood that the casing 6 or other structure carrying the needle 7 and its associated contacts is usually, though not necessarily made to be conveniently removable from the core 2 in order to permit of the introduction and removal of the line conductor in which the current flow is to be measured inside of said core. In the case of Fig. 4 the needle and its coiiperating parts may be permanently fixed in place. If desired, the resistance 15 may be formed of a column of carbon plates and the parts so adjusted that the spring 21 normally prevents the arm 18 from compressing said resistance which is therefore so high that the ammeter reads zero. If now the core 2 be slipped over the line 1 so that the flux produced causes the needle 7 to engage the contact 10', the energization of the solenoid 12 causes the resistance t9 ,be compressed against the aetion'ofthe spring 21, permitting a compensating current to flow in the winding 3 until the eflect of the line current is neutralized, when the circuit of said solenoid is broken. As before, the current indicated by the ammeter will bear a definite ratio to that in the line.

I claim I 1. The combination in an electrical instrument of a core; a winding thereon; a movable member actuated by magnetic flux in said core; a contact engaged by said member when it is deflected from a normal position; a current indicating device; a body of resistance; a source of current in circuit with said resistance, the winding and said device; an electromagnet having a movable part and in circuit with the movable member and its contact; and a contact arm connected to the movable part of the electromagnet for varying the amount of resistance in circuit when the movable member engages its contact.

2. The combination of a core adapted to be subjected to the influence of a magnetic field; a winding thereon; a source of current; a body of resistance and a current indicating device in circuit with said winding; a member movable under the action of the magnetic flux in said core; a contact engaged by said member when it is deflected;

and means in circuit with said member and contact for automatically adjusting the amount of said resistance, when the contact and member-are engaged, until the flux in the core is neutralized.

3. The combination of a core adapted to be subjected to the influence of a magnetic field; a winding thereon; a current indicating device and a source of current in the circuit with said winding; a member movable under the action ofmagnetic flux in the core; a contact engaged by said member when it is deflected; and means in circuit with said contact and member for automatically varying the current flow in the winding, when the member engages. the contact, until the flux in the core is neutralized.

4. The combination of a core adapted to be subjected to the influence of a magnetic field; a winding thereon; a current indicating device and a source of current in circuit with said winding; 21 member movableun'der the action of magnetic flux in the core; a contact engaged by said member when it is deflected; and means in circuit with said contact and member for automatically varying the current flow in the winding to bring the flux in the core to a predetermined value.

5. A current measuring instrument consisting of an annular core having ends spaced apart to permit of the introduction of a current carrying conductor; a device for indicating the presenceof flux in said core; a winding for the core; means in circuit with the winding for causing a current flow therein; means for indicating the amount of said current; and means for automatically adjusting the flow of current to an amount necessary to bring the flux in the core to a predetermined density.

6. A current measuring instrument consisting of an annular core having ends spaced apart to permit of the introduction of a conductor adapted to set up a flux in said core; a device including a movable member for indicating the presence of a flux in the core; a contact placed to cooperate with said member; means in circuit with the contact and the movable member, for causing a flux in the core opposed to that produced by the conductor within the same; means for indicating the amount of current necessary to produce the opposing flux; and means for automatically adjusting the current flow to an amount necessary to cause the flux'to be practically zero.

7. The combination of a core adapted to be subjected to the influence of a magnetic field; a winding thereon; a current indicating device, a body of resistance and a source of current all connected in circuit with said winding; a movable member mounted adjacent said core; a winding on said member; a contact mounted to be engaged by said member when it is deflected froma normal position by the action of flux in the core upon the winding carried by the movable member; and means in circuit with said latter winding and the contact for automatically adjusting the amount of said resistance in circuit to bring the current in the core winding to an amount necessary to cause the flux in the core to be substantially neutralized.

8. The combination of a core; a winding thereon; a current indicating device,a body of resistance and a source of current all connected in circuit with said winding; a member movable under the action of flux in the core; a contact placed to be engaged by said member when this is deflected; an electromagnet in circuit with said contact; and means actuated by the movable member of said electro-magnet for varying ,the amount of resistance in circuit.

9. The combination of a core adapted to be subjected to the influence of a magnetic field; a winding thereon; a current indicating device, a body of resistance and a source sisting of an annular core having ends spaced apart to permit of the introduction of a current carrying conductor; a winding for the core; means in circuit with the windingfor causing a current flow therein; means for indicating the amount of said current;

with a device for indicating the presence of flux 1n said core including a movable member and a winding thereon connected in circuit with a source of current.

11. A current measuring instrument consisting of an annular core having ends spaced apart to permit of the introduction of a current carrying conductor; a winding for the core; means in circuit with the winding forcausing a current flow therein; a device operatively associated with said means for indicating the amount of said current; a device including a movable member and a winding for indicating the presence of flux in said core; contacts placed on opposite sides of the movable member in positions to be engaged when said member is deflected by flux in the core; two solenoids respectively connected to said contacts and also in circuit with the windin on the movable member; a core for the so enoids; and means actuated by said latter core for adjusting the current flow through the winding to an amount at which the flux in the annular core is neutralized.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing Witnesses.

OTTO A. KNoPP. 

